fix select (#133)

closes #117

Reviewed-on: #133

frontend/allowance-planner-v2/src/app/pages/edit-task/edit-task.page.html

@@ -19,9 +19,9 @@
     <input id="reward" type="number" placeholder="0.00" name="price" min="0" value="0" step="0.01" formControlName="reward"/>
 
     <label>Assigned</label>
-    <select formControlName="assigned">
-      <option *ngFor="let user of users" [value]="user.id">{{ user.name }}</option>
-    </select>
+    <mat-select formControlName="assigned">
+      <mat-option *ngFor="let user of users" [value]="user.id">{{ user.name }}</mat-option>
+    </mat-select>
 
     <button type="button" [disabled]="!form.valid" (click)="submit()">
       <span *ngIf="isAddMode">Add Task</span>